The present invention relates in general to an improved system for logging a plurality of parameters in a production oil well, and in particular, it relates to a system for simultaneously providing an acoustic noise log, a temperature log, a conductivity log, and a location log in such a well.
Production oil wells, as opposed to most exploratory wells are cased with pipe sections. Production wells may produce from a plurality of locations and in such situations, a plurality of axially aligned casings may be used. Whether a production well has a single or a plurality of casings, however, the diameter of the bore hole is constricted by the casing or casings. When logging of various parameters is accomplished in such a well, four wire interconnect cable between the down-hole and up-hole components of the logging device is commonly employed. These four wires carry power from the up-hole components to the down-hole components and also carry signals from the down-hole to the up-hole components.
Among the parameters sought to be logged in production wells are acoustic noise with multiple hydrophones. (See U.S. Pat. No. 4,114,721--Glenn). Other parameters to be monitored are conductivity, temperature and depth. It would, of course, be possible to monitor each of these parameters separately. However, such an approach is time consuming and therefore costly. It would also be possible to monitor all of these parameters simultaneously by increasing the number of interconnecting wires, however, such an approach is not a practical solution because of the constraints in the bore hole diameter of production wells having a casing or casings therein. It would also be possible to simultaneously monitor each of these components by multiplexing techniques, however, such an approach requires the use of a substantial number of solid state devices in the down-hole tool. Since down-hole components are subjected to severe temperatures and pressures, such an approach greatly decreases the reliability of the resulting tool.
It would be desirable to provide a production logging system for monitoring a plurality of parameters in addition to acoustic noise with a small, compact down-hole tool without the use of multiplexing techniques.
It would also be desirable to provide such a system with the commonly employed four wire interconnecting cable between the downhole and uphole components.